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Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences
RESEARCH ARTICLE (Open Access)

Ontogenetic and intraspecific variability in otolith shape of anchoveta (Engraulis ringens) used to identify demographic units in the Pacific Southeast off Chile

Francisco Cerna https://orcid.org/0000-0002-2723-1840 A E , Juan Carlos Saavedra-Nievas A , Guido Plaza-Pasten B , Edwin Niklitschek C and Beatriz Morales-Nin D
+ Author Affiliations
- Author Affiliations

A División de Investigación Pesquera, Instituto de Fomento Pesquero, Blanco 839, Valparaíso, Chile.

B Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso, Avenida Altamirano 1480, Casilla 1020, Valparaíso, Chile.

C Centro i~mar, Universidad de Los Lagos, Carmino a Chinquihue kilómetro 6, Puerto Montt, Chile.

D Mediterranean Institute for Advanced Studies (IMEDEA), Miquel Marques 21, E-07190 Esporles, Spain.

E Corresponding author. Email: francisco.cerna@ifop.cl

Marine and Freshwater Research 70(12) 1794-1804 https://doi.org/10.1071/MF18278
Submitted: 1 August 2018  Accepted: 15 April 2019   Published: 19 August 2019

Journal Compilation © CSIRO 2019 Open Access CC BY-NC-ND

Abstract

The phenotypical variability in otolith shape of anchoveta (Engraulis ringens) was analysed in three zones (I, II and III) from north to south along the Chilean coast, using juvenile and adult fish. Generalised additive models were used to analyse shape indices and canonical discriminant analysis was used to analyse elliptical Fourier harmonics. The form factor and ellipticity indices varied significantly among the three zones, whereas roundness, circularity and rectangularity indices only showed differences between Zones I and III. Fourier reconstructed outlines for five ontogenetic stages suggested important differences among sampling zones, which were larger for sampling Zone III, where, at the same fish length, otoliths were smaller than those sampled in Zones I and II, at least at the pre-recruit stage. Elliptical Fourier descriptors showed significant differences among the three units, with a total percentage of correct classifications for juveniles of 89 and 74% for raw data and cross-validated cases respectively, compared with >85 and ~65% respectively for adult fish. The results support the hypothesis that juveniles and adults of anchoveta have remained segregated throughout their entire, or at least a fraction of, their life cycle, mainly between the extreme northward and southward zones.

Additional keywords: elliptical Fourier analysis, generalised additive model otolith shape indices, stock.


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